<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
			<script>
				var b=0;
				var c=0;
				var a="dfjd5555ffdfeww555wf";
				for(var i=0;i<20;i++){
					if(isNaN(a[i])==true){
						c+=1;
					}else{
						b+=1;
					}
					
				}
				document.write("字母个数:"+c+"数字个数:"+b);
			</script>
		</body>
</html>
